SISKIYOU COUNTY AIR POLLUTION CONTROL DISTRICT
RULE 8.4 - HEXAVALENT CHROMIUM AIRBORNE TOXIC CONTROL MEASURE - COOLING TOWERS
To comply with the California Code of Regulations, Section 93102. This airborne toxic control measure will reduce hexavalent chromium emissions from chromatic treated cooling towers and cancer incidence to the lowest level achievable through application of best available control technology at operations subject to this measure.
For purposes of this section, the following definitions shall apply:
1. Cooling Tower
Any open water recirculation device which evaporates circulating water to remove heat from a process, building, or refrigeration device, and puts the heat into the ambient air.
2. Hexavalent Chromium
A cancer-causing substance existing as part of various inorganic chromate compounds, for example, sodium dichromate or lead chromate.
3. Water Treatment Chemicals
Any combination of chemicals added to cooling tower water including tracers, corrosion inhibitors, antiscalants, dispersants, biocides.
1. Hexavalent Chromium Removal
Effective September 12, 1990 no person shall add any hexavalent chromium containing chemicals or any compound that may produce hexavalent chromium to a cooling tower operating in the District.
2. Circulating Water Concentration - Wooden Cooling Towers
Effective September 12, 1990, no person shall operate a wooden cooling tower in the District unless the following requirements are met:
a. From September 12, 1990 to March 12, 1991, hexavalent chromium levels in the circulating water are not to exceed 8 milligrams/liter of circulating water.
b. After March 12, 1991, hexavalent chromium levels in the circulating water are not to exceed 0.15 milligrams/liter of circulating water.
c. A decrease in hexavalent concentrate in the circulating water must be demonstrated each month during a period of up to six months following the compliance date in order to avoid being cited for a violation of the 0.15 milligrams/liter limit.
3. Circulating Water Concentration - Non-Wooden Cooling
Effective September 12, 1990, no person shall operate a non-wooden cooling tower unless the hexavalent chromium levels do not exceed 0.15 milligrams/liter of circulating water.
1. By December 12, 1990 any owner/operator of a cooling tower shall notify the District in writing regarding the following information about the cooling tower. Any owner/operator of a newly constructed cooling tower shall provide the District with the following information at least 90 days before the tower is operated:
a. Owner/operator of the tower
b. Location of the tower
c. Cooling tower type and material of construction
d. Whether hexavalent chromium based treatment chemicals were previously used in the cooling tower
e. If hexavalent chromium based chemicals were previously used, when they were discontinued
f. A description of the alternate treatment program chosen, as well as the circulating water monitoring plan.
E. Monitoring - General
1. Effective September 12, 1990, any person subject to the requirements of B.2. or B.3. shall test the circulating water in the cooling tower at least once every six calendar months to determine the concentration of hexavalent chromium. Testing may be discontinued when two consecutive required tests show hexavalent chromium concentrations less than 0.15 milligrams/liter of circulating water. The District may require testing of the circulating water at any time if the District has reason to believe the water may contain hexavalent chromium.
2. Any person subject to the monitoring requirements in D.1. above or E.1. below shall maintain records of the results of all required tests of circulating water for two years and provide them to the District upon request.
3. Monitoring requirements may be waived by the District for any owner/operator of a cooling tower who demonstrates to the District that the hexavalent chromium based treatment chemical has never been used in the cooling tower or has not been utilized for a period of at least one year prior to the appropriate compliance date.
F. Monitoring - Wooden Cooling Towers
1. Any person subject to the requirements of B.2.b. shall test the circulating water at least once every calendar month to determine the concentration of hexavalent chromium.
G. Determination of Hexavalent Chromium Content
1. Samples of circulating water shall be analyzed for hexavalent chromium using American Public Health Association Method 312 B or an equivalent method approved by the District.